res/drawable/focus_square_button.xml

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <!-- pressed state -->
    <item android:state_pressed="true">
        <shape android:shape="rectangle">
            <size android:width="80dp" android:height="80dp"/>
            <stroke android:width="2dp" android:color="#FFFFFF00"/>
            <solid android:color="#00FFFFFF"/>
        </shape>

    </item>

    <item>
        <shape android:shape="rectangle">
            <size android:width="80dp" android:height="80dp"/>
            <stroke android:width="0.5dp" android:color="#FFFFFF00"/>
            <solid android:color="#00FFFFFF"/>
        </shape>
    </item>

</selector>